X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Fmremap.c;h=845190898d59f206201b4b5d60f1d4534a755913;hb=4f0ddfdffc8bef3a5eb9154734d68a6053194948;hp=f343fc73a8bdd7f0ecd68fb1674438033c85cc49;hpb=8b1f3124618b54cf125dea3a074b9cf469117723;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/mremap.c b/mm/mremap.c index f343fc7..8451908 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -3,7 +3,7 @@ * * (C) Copyright 1996 Linus Torvalds * - * Address space accounting code + * Address space accounting code * (C) Copyright 2002 Red Hat Inc, All Rights Reserved */ @@ -11,46 +11,23 @@ #include #include #include +#include #include #include +#include #include #include #include #include +#include #include #include #include -static pte_t *get_one_pte_map_nested(struct mm_struct *mm, unsigned long addr) -{ - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; - pte_t *pte = NULL; - - pgd = pgd_offset(mm, addr); - if (pgd_none_or_clear_bad(pgd)) - goto end; - - pud = pud_offset(pgd, addr); - if (pud_none_or_clear_bad(pud)) - goto end; +#include "internal.h" - pmd = pmd_offset(pud, addr); - if (pmd_none_or_clear_bad(pmd)) - goto end; - - pte = pte_offset_map_nested(pmd, addr); - if (pte_none(*pte)) { - pte_unmap_nested(pte); - pte = NULL; - } -end: - return pte; -} - -static pte_t *get_one_pte_map(struct mm_struct *mm, unsigned long addr) +static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; pud_t *pud; @@ -68,41 +45,49 @@ static pte_t *get_one_pte_map(struct mm_struct *mm, unsigned long addr) if (pmd_none_or_clear_bad(pmd)) return NULL; - return pte_offset_map(pmd, addr); + return pmd; } -static inline pte_t *alloc_one_pte_map(struct mm_struct *mm, unsigned long addr) +static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; pud_t *pud; pmd_t *pmd; - pte_t *pte = NULL; pgd = pgd_offset(mm, addr); - pud = pud_alloc(mm, pgd, addr); if (!pud) return NULL; + pmd = pmd_alloc(mm, pud, addr); - if (pmd) - pte = pte_alloc_map(mm, pmd, addr); - return pte; + if (!pmd) + return NULL; + + if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr)) + return NULL; + + return pmd; } -static int -move_one_page(struct vm_area_struct *vma, unsigned long old_addr, - struct vm_area_struct *new_vma, unsigned long new_addr) +static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, + unsigned long old_addr, unsigned long old_end, + struct vm_area_struct *new_vma, pmd_t *new_pmd, + unsigned long new_addr) { struct address_space *mapping = NULL; struct mm_struct *mm = vma->vm_mm; - int error = 0; - pte_t *src, *dst; + pte_t *old_pte, *new_pte, pte; + spinlock_t *old_ptl, *new_ptl; + unsigned long old_start; + old_start = old_addr; + mmu_notifier_invalidate_range_start(vma->vm_mm, + old_start, old_end); if (vma->vm_file) { /* * Subtle point from Rajesh Venkatasubramanian: before - * moving file-based ptes, we must lock vmtruncate out, - * since it might clean the dst vma before the src vma, + * moving file-based ptes, we must lock truncate_pagecache + * out, since it might clean the dst vma before the src vma, * and we propagate stale pages into the dst afterward. */ mapping = vma->vm_file->f_mapping; @@ -111,74 +96,71 @@ move_one_page(struct vm_area_struct *vma, unsigned long old_addr, new_vma->vm_truncate_count != vma->vm_truncate_count) new_vma->vm_truncate_count = 0; } - spin_lock(&mm->page_table_lock); - src = get_one_pte_map_nested(mm, old_addr); - if (src) { - /* - * Look to see whether alloc_one_pte_map needs to perform a - * memory allocation. If it does then we need to drop the - * atomic kmap - */ - dst = get_one_pte_map(mm, new_addr); - if (unlikely(!dst)) { - pte_unmap_nested(src); - if (mapping) - spin_unlock(&mapping->i_mmap_lock); - dst = alloc_one_pte_map(mm, new_addr); - if (mapping && !spin_trylock(&mapping->i_mmap_lock)) { - spin_unlock(&mm->page_table_lock); - spin_lock(&mapping->i_mmap_lock); - spin_lock(&mm->page_table_lock); - } - src = get_one_pte_map_nested(mm, old_addr); - } - /* - * Since alloc_one_pte_map can drop and re-acquire - * page_table_lock, we should re-check the src entry... - */ - if (src) { - if (dst) { - pte_t pte; - pte = ptep_clear_flush(vma, old_addr, src); - - /* ZERO_PAGE can be dependant on virtual addr */ - pte = move_pte(pte, new_vma->vm_page_prot, - old_addr, new_addr); - set_pte_at(mm, new_addr, dst, pte); - } else - error = -ENOMEM; - pte_unmap_nested(src); - } - if (dst) - pte_unmap(dst); + /* + * We don't have to worry about the ordering of src and dst + * pte locks because exclusive mmap_sem prevents deadlock. + */ + old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); + new_pte = pte_offset_map_nested(new_pmd, new_addr); + new_ptl = pte_lockptr(mm, new_pmd); + if (new_ptl != old_ptl) + spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); + arch_enter_lazy_mmu_mode(); + + for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, + new_pte++, new_addr += PAGE_SIZE) { + if (pte_none(*old_pte)) + continue; + pte = ptep_clear_flush(vma, old_addr, old_pte); + pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); + set_pte_at(mm, new_addr, new_pte, pte); } - spin_unlock(&mm->page_table_lock); + + arch_leave_lazy_mmu_mode(); + if (new_ptl != old_ptl) + spin_unlock(new_ptl); + pte_unmap_nested(new_pte - 1); + pte_unmap_unlock(old_pte - 1, old_ptl); if (mapping) spin_unlock(&mapping->i_mmap_lock); - return error; + mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end); } -static unsigned long move_page_tables(struct vm_area_struct *vma, +#define LATENCY_LIMIT (64 * PAGE_SIZE) + +unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long old_addr, struct vm_area_struct *new_vma, unsigned long new_addr, unsigned long len) { - unsigned long offset; + unsigned long extent, next, old_end; + pmd_t *old_pmd, *new_pmd; - flush_cache_range(vma, old_addr, old_addr + len); + old_end = old_addr + len; + flush_cache_range(vma, old_addr, old_end); - /* - * This is not the clever way to do this, but we're taking the - * easy way out on the assumption that most remappings will be - * only a few pages.. This also makes error recovery easier. - */ - for (offset = 0; offset < len; offset += PAGE_SIZE) { - if (move_one_page(vma, old_addr + offset, - new_vma, new_addr + offset) < 0) - break; + for (; old_addr < old_end; old_addr += extent, new_addr += extent) { cond_resched(); + next = (old_addr + PMD_SIZE) & PMD_MASK; + if (next - 1 > old_end) + next = old_end; + extent = next - old_addr; + old_pmd = get_old_pmd(vma->vm_mm, old_addr); + if (!old_pmd) + continue; + new_pmd = alloc_new_pmd(vma->vm_mm, new_addr); + if (!new_pmd) + break; + next = (new_addr + PMD_SIZE) & PMD_MASK; + if (extent > next - new_addr) + extent = next - new_addr; + if (extent > LATENCY_LIMIT) + extent = LATENCY_LIMIT; + move_ptes(vma, old_pmd, old_addr, old_addr + extent, + new_vma, new_pmd, new_addr); } - return offset; + + return len + old_addr - old_end; /* how much done */ } static unsigned long move_vma(struct vm_area_struct *vma, @@ -191,7 +173,9 @@ static unsigned long move_vma(struct vm_area_struct *vma, unsigned long new_pgoff; unsigned long moved_len; unsigned long excess = 0; + unsigned long hiwater_vm; int split = 0; + int err; /* * We'd prefer to avoid failure later on in do_munmap: @@ -200,6 +184,18 @@ static unsigned long move_vma(struct vm_area_struct *vma, if (mm->map_count >= sysctl_max_map_count - 3) return -ENOMEM; + /* + * Advise KSM to break any KSM pages in the area to be moved: + * it would be confusing if they were to turn up at the new + * location, where they happen to coincide with different KSM + * pages recently unmapped. But leave vma->vm_flags as it was, + * so KSM can come around to merge on vma and new_vma afterwards. + */ + err = ksm_madvise(vma, old_addr, old_addr + old_len, + MADV_UNMERGEABLE, &vm_flags); + if (err) + return err; + new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); if (!new_vma) @@ -229,17 +225,24 @@ static unsigned long move_vma(struct vm_area_struct *vma, } /* - * if we failed to move page tables we still do total_vm increment - * since do_munmap() will decrement it by old_len == new_len + * If we failed to move page tables we still do total_vm increment + * since do_munmap() will decrement it by old_len == new_len. + * + * Since total_vm is about to be raised artificially high for a + * moment, we need to restore high watermark afterwards: if stats + * are taken meanwhile, total_vm and hiwater_vm appear too high. + * If this were a serious issue, we'd add a flag to do_munmap(). */ + hiwater_vm = mm->hiwater_vm; mm->total_vm += new_len >> PAGE_SHIFT; - __vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); + vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); if (do_munmap(mm, old_addr, old_len) < 0) { /* OOM: unable to split vma, just get accounts right */ vm_unacct_memory(excess >> PAGE_SHIFT); excess = 0; } + mm->hiwater_vm = hiwater_vm; /* Restore VM_ACCOUNT if one or two pieces of vma left */ if (excess) { @@ -251,13 +254,144 @@ static unsigned long move_vma(struct vm_area_struct *vma, if (vm_flags & VM_LOCKED) { mm->locked_vm += new_len >> PAGE_SHIFT; if (new_len > old_len) - make_pages_present(new_addr + old_len, - new_addr + new_len); + mlock_vma_pages_range(new_vma, new_addr + old_len, + new_addr + new_len); } return new_addr; } +static struct vm_area_struct *vma_to_resize(unsigned long addr, + unsigned long old_len, unsigned long new_len, unsigned long *p) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = find_vma(mm, addr); + + if (!vma || vma->vm_start > addr) + goto Efault; + + if (is_vm_hugetlb_page(vma)) + goto Einval; + + /* We can't remap across vm area boundaries */ + if (old_len > vma->vm_end - addr) + goto Efault; + + if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { + if (new_len > old_len) + goto Efault; + } + + if (vma->vm_flags & VM_LOCKED) { + unsigned long locked, lock_limit; + locked = mm->locked_vm << PAGE_SHIFT; + lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; + locked += new_len - old_len; + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) + goto Eagain; + } + + if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) + goto Enomem; + + if (vma->vm_flags & VM_ACCOUNT) { + unsigned long charged = (new_len - old_len) >> PAGE_SHIFT; + if (security_vm_enough_memory(charged)) + goto Efault; + *p = charged; + } + + return vma; + +Efault: /* very odd choice for most of the cases, but... */ + return ERR_PTR(-EFAULT); +Einval: + return ERR_PTR(-EINVAL); +Enomem: + return ERR_PTR(-ENOMEM); +Eagain: + return ERR_PTR(-EAGAIN); +} + +static unsigned long mremap_to(unsigned long addr, + unsigned long old_len, unsigned long new_addr, + unsigned long new_len) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + unsigned long ret = -EINVAL; + unsigned long charged = 0; + unsigned long map_flags; + + if (new_addr & ~PAGE_MASK) + goto out; + + if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) + goto out; + + /* Check if the location we're moving into overlaps the + * old location at all, and fail if it does. + */ + if ((new_addr <= addr) && (new_addr+new_len) > addr) + goto out; + + if ((addr <= new_addr) && (addr+old_len) > new_addr) + goto out; + + ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); + if (ret) + goto out; + + ret = do_munmap(mm, new_addr, new_len); + if (ret) + goto out; + + if (old_len >= new_len) { + ret = do_munmap(mm, addr+new_len, old_len - new_len); + if (ret && old_len != new_len) + goto out; + old_len = new_len; + } + + vma = vma_to_resize(addr, old_len, new_len, &charged); + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); + goto out; + } + + map_flags = MAP_FIXED; + if (vma->vm_flags & VM_MAYSHARE) + map_flags |= MAP_SHARED; + + ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff + + ((addr - vma->vm_start) >> PAGE_SHIFT), + map_flags); + if (ret & ~PAGE_MASK) + goto out1; + + ret = move_vma(vma, addr, old_len, new_len, new_addr); + if (!(ret & ~PAGE_MASK)) + goto out; +out1: + vm_unacct_memory(charged); + +out: + return ret; +} + +static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) +{ + unsigned long end = vma->vm_end + delta; + if (end < vma->vm_end) /* overflow */ + return 0; + if (vma->vm_next && vma->vm_next->vm_start < end) /* intersection */ + return 0; + if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start, + 0, MAP_FIXED) & ~PAGE_MASK) + return 0; + return 1; +} + /* * Expand (or shrink) an existing mapping, potentially moving it at the * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) @@ -269,6 +403,7 @@ unsigned long do_mremap(unsigned long addr, unsigned long old_len, unsigned long new_len, unsigned long flags, unsigned long new_addr) { + struct mm_struct *mm = current->mm; struct vm_area_struct *vma; unsigned long ret = -EINVAL; unsigned long charged = 0; @@ -290,28 +425,10 @@ unsigned long do_mremap(unsigned long addr, if (!new_len) goto out; - /* new_addr is only valid if MREMAP_FIXED is specified */ if (flags & MREMAP_FIXED) { - if (new_addr & ~PAGE_MASK) - goto out; - if (!(flags & MREMAP_MAYMOVE)) - goto out; - - if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) - goto out; - - /* Check if the location we're moving into overlaps the - * old location at all, and fail if it does. - */ - if ((new_addr <= addr) && (new_addr+new_len) > addr) - goto out; - - if ((addr <= new_addr) && (addr+old_len) > new_addr) - goto out; - - ret = do_munmap(current->mm, new_addr, new_len); - if (ret) - goto out; + if (flags & MREMAP_MAYMOVE) + ret = mremap_to(addr, old_len, new_addr, new_len); + goto out; } /* @@ -320,75 +437,37 @@ unsigned long do_mremap(unsigned long addr, * do_munmap does all the needed commit accounting */ if (old_len >= new_len) { - ret = do_munmap(current->mm, addr+new_len, old_len - new_len); + ret = do_munmap(mm, addr+new_len, old_len - new_len); if (ret && old_len != new_len) goto out; ret = addr; - if (!(flags & MREMAP_FIXED) || (new_addr == addr)) - goto out; - old_len = new_len; + goto out; } /* - * Ok, we need to grow.. or relocate. + * Ok, we need to grow.. */ - ret = -EFAULT; - vma = find_vma(current->mm, addr); - if (!vma || vma->vm_start > addr) - goto out; - if (is_vm_hugetlb_page(vma)) { - ret = -EINVAL; + vma = vma_to_resize(addr, old_len, new_len, &charged); + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); goto out; } - /* We can't remap across vm area boundaries */ - if (old_len > vma->vm_end - addr) - goto out; - if (vma->vm_flags & VM_DONTEXPAND) { - if (new_len > old_len) - goto out; - } - if (vma->vm_flags & VM_LOCKED) { - unsigned long locked, lock_limit; - locked = current->mm->locked_vm << PAGE_SHIFT; - lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; - locked += new_len - old_len; - ret = -EAGAIN; - if (locked > lock_limit && !capable(CAP_IPC_LOCK)) - goto out; - } - if (!may_expand_vm(current->mm, (new_len - old_len) >> PAGE_SHIFT)) { - ret = -ENOMEM; - goto out; - } - - if (vma->vm_flags & VM_ACCOUNT) { - charged = (new_len - old_len) >> PAGE_SHIFT; - if (security_vm_enough_memory(charged)) - goto out_nc; - } /* old_len exactly to the end of the area.. - * And we're not relocating the area. */ - if (old_len == vma->vm_end - addr && - !((flags & MREMAP_FIXED) && (addr != new_addr)) && - (old_len != new_len || !(flags & MREMAP_MAYMOVE))) { - unsigned long max_addr = TASK_SIZE; - if (vma->vm_next) - max_addr = vma->vm_next->vm_start; + if (old_len == vma->vm_end - addr) { /* can we just expand the current mapping? */ - if (max_addr - addr >= new_len) { + if (vma_expandable(vma, new_len - old_len)) { int pages = (new_len - old_len) >> PAGE_SHIFT; vma_adjust(vma, vma->vm_start, addr + new_len, vma->vm_pgoff, NULL); - current->mm->total_vm += pages; - __vm_stat_account(vma->vm_mm, vma->vm_flags, - vma->vm_file, pages); + mm->total_vm += pages; + vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); if (vma->vm_flags & VM_LOCKED) { - current->mm->locked_vm += pages; - make_pages_present(addr + old_len, + mm->locked_vm += pages; + mlock_vma_pages_range(vma, addr + old_len, addr + new_len); } ret = addr; @@ -402,29 +481,33 @@ unsigned long do_mremap(unsigned long addr, */ ret = -ENOMEM; if (flags & MREMAP_MAYMOVE) { - if (!(flags & MREMAP_FIXED)) { - unsigned long map_flags = 0; - if (vma->vm_flags & VM_MAYSHARE) - map_flags |= MAP_SHARED; - - new_addr = get_unmapped_area(vma->vm_file, 0, new_len, - vma->vm_pgoff, map_flags); + unsigned long map_flags = 0; + if (vma->vm_flags & VM_MAYSHARE) + map_flags |= MAP_SHARED; + + new_addr = get_unmapped_area(vma->vm_file, 0, new_len, + vma->vm_pgoff + + ((addr - vma->vm_start) >> PAGE_SHIFT), + map_flags); + if (new_addr & ~PAGE_MASK) { ret = new_addr; - if (new_addr & ~PAGE_MASK) - goto out; + goto out; } + + ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); + if (ret) + goto out; ret = move_vma(vma, addr, old_len, new_len, new_addr); } out: if (ret & ~PAGE_MASK) vm_unacct_memory(charged); -out_nc: return ret; } -asmlinkage unsigned long sys_mremap(unsigned long addr, - unsigned long old_len, unsigned long new_len, - unsigned long flags, unsigned long new_addr) +SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, + unsigned long, new_len, unsigned long, flags, + unsigned long, new_addr) { unsigned long ret;